P030B
Ignition A Control Signal Circuit Low
Ignition A Control Signal Circuit Low: the signal voltage is below the expected range. This line drives an ignition coil group; a fault causes misfire on those cylinders.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Short to groundCommon
- Connector pins corroded - high contact resistanceLess likely
- Harness chafing through insulationLess likely
Parts involved
- Ignition Coil
P030B is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.